The experimental group will receive Bubble PEP therapy and Segmental Breathing along with conventional chest physiotherapy and mobility training. Bubble PEP will be performed using a bottle device where children exhale through a water-submerged tube, creating resistance to improve lung expansion and secretion clearance (10 repetitions, progressing from 1 to 3 sets over 14 days). Segmental Breathing will focus on localized lung expansion with therapist-guided tactile feedback, performed at six breaths per minute, progressing from 1 to 3 sets. Chest percussion will be applied for 2-5 minutes with rest intervals, and walking distance will increase from 1 to 5 meters. All sessions will be conducted once daily for two weeks.

Participants in the control group will receive Incentive Spirometry along with conventional chest physiotherapy and mobility training. Incentive Spirometry will be used to encourage sustained maximal inspiration, thereby promoting lung expansion and improving ventilation. Each session will include three repetitions per side during Days 1-3, five repetitions per side during Days 4-7, and ten repetitions per side during Days 8-14, performed in one set per session. Chest percussion will be administered on the contralateral side to facilitate secretion mobilization, performed for two minutes on Days 1-3, three minutes on Days 4-7, and five minutes on Days 8-14, with 15 seconds of rest after each minute. Mobility training will include walking exercises, starting from one meter on Day 1, increasing to three meters by Day 3, and progressing to five meters from Day 4 onward, performed in two sets during Days 8-14. All sessions will be conducted once daily for two weeks.